1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly to a driving module for a liquid crystal display panel and a liquid crystal display device having the same capable of inspecting the effectiveness of a driving signal applied to a display cell circuit of the liquid crystal panel and a wiring state of driving signal input/output lines.
2. Description of the Related Art
Recently, as information technology is developed, information processing devices, such as computers, make great strides. The advance of the information processing technology leads to the development of the monitor device which displays information outputted from the information processing device.
The monitor device is generally classified into a CRT (cathode ray tube) type monitor device which uses the features of the CRT, and a liquid crystal unit type monitor device which adopts physical and optical features of liquid crystal. The liquid crystal unit type monitor device has a compact size and a light weight with a low power consumption as compared with the CRT type monitor device. As a result, the liquid crystal unit type monitor device is widely used as a display device of a portable computer, as a monitor of a desk top computer and as a monitor of a high definition visual instrument.
FIG. 1 shows an exploded perspective view of a conventional liquid crystal display device 100.
Referring to FIG. 1, the liquid crystal display device 100 has a liquid crystal display module 130 which displays an image by receiving an image signal, a front case 110 and a rear case 120 that are coupled to each other so as to receive the liquid crystal display module 130. The liquid crystal display module 130 includes a display unit 170 and a back light assembly 150 for providing a light to the display unit 170.
The display unit 170 has a liquid crystal display panel 171 for displaying the image, a data side printed circuit board 176, a gate side printed circuit board 175, a data side tape carrier package 178 and a gate side tape carrier package 174.
The liquid crystal display panel 171 has a thin film transistor substrate 172, a color filter board 173 and a liquid crystal (not shown).
The thin film transistor substrate 172 is a transparent glass substrate on which thin film transistors arranged in a matrix are formed. Data lines are connected to a source terminal of the thin film transistor, and gate lines are connected to a gate terminal of the thin film transistor. In addition, pixel electrodes consisting of indium tin oxide (ITO), which is transparent conductive material, is formed on a drain terminal of the thin film transistor.
The color filter board 173 is positioned opposite to the thin film transistor substrate 172. R.G.B pixels are formed on the color filter board 173 by a thin film manufacturing process. When the light passes through the R.G.B pixels of the color filter board 173, predetermined colors are generated. A common electrode of ITO is coated on a front portion of the color filter board 173.
When the electric power is applied to gate and source terminals of the transistor of the thin film transistor substrate, the thin film transistors are turned-on so that an electric field is formed between the pixel electrode and the common electrode of the color filter board. Alignment angles of molecules of the liquid crystal injected between the thin film transistor substrate 172 and the color filter board 173 are changed by the electric field, so the light transmission rate according to the alignment angles of molecules of the liquid crystal so that desired pixels are obtained.
In order to control the alignment angles and alignment time of molecules of the liquid crystal, a driving signal and a timing signal are applied to the gate line and the data line of the thin film transistor, respectively. As shown in FIG. 1, the data side tape carrier package 178, which is a flexible printed circuit board, is attached to the source side of the liquid crystal display panel 171 for applying the data driving signal. In addition, the gate side tape carrier package 174, which is a flexible printed circuit board, is attached to the gate side of the liquid crystal display panel 171 for applying the gate driving signal.
The data side printed circuit board 176 and the gate side printed circuit board 175, which apply driving signals to the data line and the gate line by receiving the image signal from outside, are connected to the data side tape carrier package 178 and the gate side tape carrier package 174, respectively. A source part receives the image signal from an information processing device (not shown), such as a computer, and applies the data driving signal to the liquid crystal display device 171. The source part is formed on the data side printed circuit board 176. A gate part is formed on the gate side printed circuit board 175 so as to apply the gate driving signal to the gate line of the liquid crystal display panel 171. That is, the data side printed circuit board 176 and the gate side printed circuit board 175 generates the gate driving signal, the data driving signal and a plurality of timing signals for determining the time for applying the gate and data driving signals, so that the gate driving signal is applied to the gate line through the gate side tape carrier package 174 and the data driving signal is applied to the data line through the data side tape carrier package 178.
The back light assembly 150 is provided below the display unit 170 so as to uniformly apply the light to the display unit 170. The back light assembly 150 has a lamp unit 151 which is positioned at an end portion of the liquid crystal display module 130 so as to generate the light, a light guide plate 152 for guiding the light towards the display unit 170, a plurality of optical sheets 153 for making the luminance of the light irradiated from the light guide plate 152 to be uniform, and a reflection plate 154 which is positioned below the light guide plate 152 so as to reflect the light leaking from the light guide plate 152, thereby improving the light efficiency.
The display unit 170 and the back light assembly 150 is fixedly supported by a mold frame 131, which is a container for receiving the display unit 170 and the back light assembly 150. A chassis 140 is provided to secure the position of the display unit 170.
As thin film manufacturing technology develops, controllers placed in the gate side printed circuit board 175 for processing the gate signal can be placed in the data side printed circuit board 176 without enlarging the area of the data side printed circuit board 176. That is, signal transmission lines for transmitting the gate driving signal or other signals are only formed in the data side printed circuit board 176 so as to transmit the gate driving signal inputted from the data side printed circuit board 176 to the gate line through the gate side tape carrier package 174.
However, in the above-mentioned conventional liquid crystal display device, it is impossible to inspect the wiring state of the signal transmission lines for the gate and the effectiveness of the gate driving signal. Particularly, since the gate side printed circuit board 175 is integrated with the data side printed circuit board 176, only are the signal transmission lines for the gate driving signal complicatedly formed in the gate side tape carrier package 175 so that the wiring state of the signal transmission lines and the effectiveness of the driving signal cannot be properly inspected.